Leukocyte infiltrates into or around
tumor cell nests are found in the context of protumorigenic
inflammation and anticancer immunosurveillance. Hence, the detailed composition, density, architecture, and function of leukocyte infiltrates must be analyzed to understand their prognostic impact. The ectopic presence within
tumors of high endothelial venule cells, which are normally characteristic for secondary lymphoid organs, correlates with a more pronounced infiltration by T lymphocytes and has a positive predictive impact on local advanced
breast cancer treated with
neoadjuvant chemotherapy. Recent progress in the field indicates that immune infiltrates of the primary
tumors, as well as of
metastases, are not only independent prognostic
biomarkers but can also constitute predictive factors, suggesting that the pretherapeutic immune response can determine the efficacy of conventional
chemotherapies. Moreover, accumulating evidence indicates that
chemotherapy can stimulate anticancer immune responses coupled with an increased intratumoral lymphoid infiltration, which correlates with
tumor mass reduction and patient survival. Improved methods for the automation of immunohistochemistry and digitalized image analyses will pave the way to an improved understanding of the complex interplay between
cancer parenchyma, stroma, and immune effectors, as well as to the routine evaluation of immune-related parameters to the clinical management of
cancer patients.